The field of the disclosure relates generally to gas turbine engines and, more particularly, to a method and apparatus for cooling an undercowl space in gas turbine engines.
Gas turbine engines typically include an undercowl space or engine core compartment as a part of the engine architecture. As gas turbine engine efficiency is improved, pressure ratios of fans and compressors, internal engine temperatures are expected to rise substantially, resulting in higher temperature for the engine core compartment and components. Engine core compartment components include electronics and other line replaceable units (LRUs). Such electronic components in known gas turbine engines, including full authority digital engine (or electronics) controls (FADECs), may be particularly sensitive to increasing engine core compartment temperatures both during gas turbine engine operation and during thermal soakback after engine shutdown. Although the electronics are not located in the hottest portion of the engine, such as those portions exposed directly to combustion products, heat from various hot portions of an operating gas turbine can be transferred to the location of the electronics, causing the temperature of the electronics to rise.
In addition to experiencing elevated temperatures during operation, the electronics may be exposed to even higher temperatures during the period after engine shut down. During this time period, the hot portions of the engine continue to radiate and conduct heat into the surrounding engine mass as they cool, but there is no airflow through the engine to help carry heat away from the rest of the engine. As a result, the temperature of some of the electronics may actually rise as the hottest engine portions cool down. Electronics temperatures can exceed 500° F. during this period of time typically referred to as “soakback.”
Such temperatures can have undesirable effects on electrical and electronic components. For example, the components that make up electronics equipment can break down. While an abrupt catastrophic failure of an electronic component may not always occur, progressive breakdown due to elevated temperature and thermal cycling can reduce the usable lifetime of such electronic components.
Known systems with radiation shields add weight to gas turbine engines and, therefore, increase the SFC. Where such components are placed at remote locations in the engine, increases in the length of connecting cables also increases engine weight and tends to increase SFC while also complicating maintenance activities. Furthermore, in such known gas turbine engines, such problems are compounded during soakback when there is no cooling flow. An extended delay after operation of such known gas turbine engines before servicing them may be required.